Oral cancers are devastating malignancies that account for approximately 5% of cancer patients. The majority of oral cancers are squamous cell carcinomas, and most develop from precancerous leukoplakias, white epithelial lesions on the lining tissues of the oral cavity [i], Up to 40% of leukoplakia lesions are transformed to cancer [2], Current approaches for the early detection of malignancies from precancerous leukoplakia include regular surveillance in conjunction with biopsy and surgical excision, but these do not contribute to non-invasive early diagnosis. Physical Optics Corporation (POC) proposes to develop an improved photodynamic drug detection imaging system (PD3) as a sensitive and non-invasive approach for the early diagnosis of oral squamous cell carcinoma, and for monitoring the effectiveness of photodynamic therapy of the cancer. The novelty of PD3 system lies in its use of a near-infrared laser to excite fluorescence in injected photodynamic drugs. Since the transformation from leukoplakia to squamous cancer takes place on the oral mucosa, it is readily detected by means of optical technology. The Phase I project will focus on demonstrating the feasibility of this technology based on the detection of early squamous cell carcinoma (SC) transformed from the leukoplakia in the oral cavity. PROPOSED COMMERCIAL APPLICATION: Leukoplakia, the most frequent precancerous lesion of the oral cavity, occurs in l% to 4% of the general population in the U.S. Up to 40% of leukoplakia lesion are transformed to cancer, usually to squamous cell carcinoma. The proposed fluorescence-inducing fiber optic technology will be valuable for cost-effective diagnosis of oral cancer, simplifying the operation and improving its sensitivity. This,project will lead to the development of a low- cost portable office device for monitoring the early diagnosis of malignant transformation of oral and other tumors.